This invention relates to a process for treating a coffee oil intended to be contacted with a frost charged with coffee aromas.
The production of soluble coffee powder by spray-drying or freeze-drying of a coffee extract obtained by percolation of an extraction liquid through cells filled with ground roasted coffee is known to produce an end product which does not have the aroma of a roasted coffee.
Various solutions have been proposed in which an oil, generally a coffee oil, is enriched with coffee aromas and then sprayed onto the soluble coffee powder. The main source used for the aromas are the aromas given off by the ground roasted coffee.
Thus, it is known to circulate an inert gas, such as carbon dioxide, through a ground roasted coffee. This inert gas becomes charged with aromas, and a frost is formed by condensation of the carbon dioxide-entrained moisture and aromas. This frost is then contacted with an oil which thus partly recovers the aromas present in the frost. This may be done by directly contacting the oil with the frost consisting of carbon dioxide, water and aromas. Another method of contacting is to sublimate the carbon dioxide and to contact the residual aqueous phase charged with aromas with the oil. The oil obtained, which is enriched with aromas, may then be re-incorporated in a soluble coffee powder.
The coffee oil may be an oil obtained by pressing roasted coffee which has not been extracted or, more often, an oil obtained from the grounds resulting from the extraction of ground roasted coffee with water. The oil obtained from non-extracted roasted coffee produces by-products, such as the press cake, which are difficult to utilize. In addition, the pressing of non-extracted roasted coffee involves losses of aromas which escape during pressing on are destroyed by the temperatures reached during pressing.
Contacting of the oil either with the frost charged with aromas or with the residual aqueous phase produces an emulsion of oil and water. However, it is not desirable to spray an oil and water emulsion onto a coffee nowder for various reasons. Firstly, the emulsion does not always have the same characteristics so that the process does not have the uniformity and reproducibility necessary for an industrial process. Secondly, the presence of water can be troublesome to the stability of the aromas. It is for this reason that it is advisable to separate the oil from the water it contains.